Gabrielle Union's new book is a ''love letter'' to her daughter.

The 'Being Mary Jane' star has penned a new children's book titled 'Welcome to the Party', and says the tome is designed as a sweet message to her 18-month-old daughter Kaavia - whom she has with her husband Dwyane Wade - to celebrate her ''non-traditional'' birth via surrogate mother.

She said: ''I wanted to create a love letter to my daughter to let her know that even though her entry into our family was a bit non-traditional, we love her and wanted her. And she is celebrated.''

Gabrielle also wants to dedicate the book to all ''non-traditional families'', as a way of honouring her own home life as stepmother to Dwyane's children from previous relationships - Zaire, 18, Zaya, 12, and Xavier, six.

She added: ''This is also my love letter to every non-traditional family, blended families, that no matter how you became a new family, it is beautiful and real.''

Kaavia is Gabrielle's first child, and so the 47-year-old actress says she often finds herself looking to her spouse for parenting tips.

She explained: ''He's been a parent literally half his adult life. So, especially when she first arrived, I deferred to him, because he's a vet. There's only so much reading that one can do, so I very much followed his lead.''

And the 'LA's Finest' star also praised her 12-year-old stepdaughter Zaya - who was born a boy named Zion - for helping to change the way she thinks about raising children, as she recently came out as transgender.

Gabrielle told People magazine: ''It's interesting because Kaav arrived before Zaya's transition. Zaya had identified as gender nonconforming. And so we really worked a lot on unlearning so much of what we thought we knew about identity and gender expression and gender norms. We put so much effort into raising her differently and not trying to predetermine who she was.''

'Welcome to the Party' was released on May 5.